Crystallizing evaporators, vertical current classifiers and the like



R. S. COOK CRYSTALLIZING EVAPORATORS, VERTICAL Oct. 1, 1957 CURRENTCLASSIFIERS AND THE LIKE Filed Nov. 14, 1955 INVENTOR ROBERT 8. 000K m aM Unitccl States Patent CRYSTALLIZING EVAPORATORS, VERTICAL CURRENTCLASSIFIERS AND THE LIKE Robert 5. Cook, B fialo, N. Y. ApplicationNovember 14, 1955, Serial No. 546,448

Cla ms. (Cl.- 159- -45) This invention is a continuation in part ofapplicants prior application, Serial No. 280,147, filed April 2, 1952,and now abandoned.

The invention relates to an improvement for efiecting the conditions inwhich crystals grow or settle in any type of device in which aclassifying influence may be of advang h ther it be n a crystall ingexap t r or hydraulic classifier not necessarily involved withevaporation.

In its application to a crystallizing evaporator, the objective is toprovide more favorable crystallizing and vaporizing conditions whichwill better promote the growth of the smaller crystals. In the case ofan hydraulic classifier the object is to promote the more completeseparation of small crystals from larger ones. This latter objective isalso valid for a crystallizing evaporator, in that more small crystalsmay be detained for further growth in an evaporator operating on acontinuous flow basis.

In a crystallizing evaporator, conditions more favorable to the growthof crystals and to the suppression of formation of new crystals will beimproved by reducing the vaporizing potential, which is usuallyevaluated in terms of the elevation of the liquid temperature above thatat which the liquid would boil at the pressure existing at the surface.One of the objects of the improvement is to reduce the vaporizingpotential without increasing the circulation of liquor through the heatexchange element.

Another object of the invention with respect to evaporation is toproduce a pattern of boiling and flow within the vapor releasing bodywhich is more stable and uniform in order to give a more efiicientdisengagement of vapor in the available space, resulting in a consequentgain in capacity and a reduction of formation of aggregate on the insidesurfaces.

I attain these objectives with the structure and arrangement illustratedin the accompanying drawing, in which Figure 1 is a half section takenvertically on a conventional cone bottom tank with cylindrical uppersection, which is customarily used in the settling or classifying ofsolids against a rising current of fluid, or as the liquor section of avapor releasing body, usually known as a vapor body or chamber orevaporator body. Figure 2 is a full plan view of the arrangement shownin half section in Figure 1.

In Figure l, the whole unit, designated by the reference number 1,represents a type of vertical current classifier or the liquor sectionof an evaporator body. The unit has a fluid entrance 2 into a primarymixing chamber 3. A second mixing chamber 4 is placed around and abovethe first mixing chamber 3 in substantially the same relation that thefirst mixing chamber 3 is placed with respect to the fluid entrance 2. Athird mixing chamber 5 is shown around and above the second mixingchamber 4 in like manner. Additional stages may be added in like manneror the invention used in its elementary form with only one mixingchamber.

Each mixing chamber is attached to the bottom of the vessel by joining asubstantial portion of its lower end periphery to the bottom of theclassifier or evaporator r 2,808,103 IC Patented Oct. 1, 1957 chamber.The portion of the lower end so joined is approximately semicircular inextent when projected onto a plane perpendicular to the longitudinalaxis of the mixing chamber. The non-contacting portion of the lower endperiphery of each mixing chamber forms a substantial opening, designatedby the numbers 6, 7, and 8 for the respective chambers. These openingsare for the free entry and recirculation of the surrounding liquid withits suspended salt.

The semi-annular section 9 is used in the classifier application tospread the upflow over about one half of the vessel periphery andCollecting the upflow for .eduction at the outlet 10. The bottom outlet11 is for the eduction of the downflow of liquid with the coarsercrystals.

When this mixing chamber arrangement is used in the lower section of anevaporator chamber, liquor enters at a predetermined velocity throughthe entry 2 at a temperature above that at which it will boil at theliquidvapor interface in the evaporator chamber. At this enteringvelocity, the fluid has the energy to aspirate the liquid contents ofthe body through the openings 6, 7, and 8 into the respective mixingchambers, the respective stage mixtures being discharged at the exitends 12, 13, and 14. The temperature of the entering fluid is therebyreduced, thus reducing its potential flashing range while spreading itinto a larger mass of fluid. Boiling is suppressed at the lower depthsdue to reduction of temperature upon mixing. As the mixture rises, vaporseparates from the mixture, leaving the greater part of the liquid torecirculate with its suspended salt toward the bottom outlet 11. As thesuspension passes downward past the respective entrances to the mixingchambers, the influence toward recirculation becomes greater and thesmaller particles will be more liable to follow the recirculating streamthan the larger ones, so that the net downflow of mixture will contain ahigher percentage of larger particles, which is desirable.

The operation of the invention in a vessel acting as a classifierwithout the boiling influence is the same as that just described exceptthat no vapor separation occurs and a portion of the efiiuent liquidrises with a predominance of small particles in suspension to be carriedto the outlet 10.

Having described and explained the application of the invention withrespect to crystallizing type evaporators and vertical current solidparticle classifiers, I claim:

1. The improvement in crystallizing type evaporators and verticalcurrent solid particle classifiers or the like, comprising asubstantially cylindroidal mixing chamber attached through a portion ofits basal periphery in contact with the bottom of an evaporator orclassifier body, the mixing chamber being positioned eccentrically inthe vertically projected area of said bottom, said contact being insubstantially symmetrical enveloping arrangement with an opening in saidbottom, the remaining part of noncontacting basal periphery constitutinga substantial opening at the basal end of said mixing chamber, saidopening being directed to the center of said bottom.

2. An evaporator chamber in which a substantially cylindroidal mixingchamber is attached through a portion of its basal periphery in contactwith the inner surface of the bottom of said evaporator chamber, themixing chamber positioned eccentrically in the bottom of said evaporatorchamber, the contacting portion of the mixing chamber basal endperiphery being in substantially symmetrical enveloping arrangement withan opening in said evaporator chamber bottom, the remaining portion ofnon-contacting basal end periphery constituting a substantial opening atthe basal end of said mixing chamber, said opening being directed to thecenter of the evaporator chamber bottom.

3. An evaporator body in which a nested arrangement of a multiplicity ofsubstantially cylindroidal mixingchambers is attached through a portionof each mixing chamber basal end periphery in approximate semicircularcontact with the inner surface of the bottom of said evaporator body,the assembly of mixing chambers in nested arrangement being positionedeccentrically on the bottom of the evaporator body, the contactingportion of the innermost mixing chamber being in substantiallysymmetrical enveloping arrangement with an opening in the evaporatorbody bottom, the contacting portions of each surrounding mixing chamberbeing in substantially symmetrical enveloping arrangement with the nextinner mixing chamber, the remaining non-contacting portion of eachmixing chamber basal end periphery constituting a substantial opening atthe basal end of each mixing chamher, said opening of each mixingchamber being directed to the center of the evaporator body bottom.

4. A vertical current solid particle classifier in which a substantiallycylindroidal mixing chamber is attached through a portion of its basalperiphery in contact with the inner surface of the bottom of saidclassifier, the mixing chamber being positioned eccentrically on saidbottom, said contacting portion of basal periphery being insubstantially symmetrical enveloping arrangement with an opening in saidbottom, the remaining portion of noncontacting basal peripheryconstituting a substantial opening at the basal end of said mixingchamber, said opening being directed to the center of said bottom.

5. A vertical current solid particle classifier in which a nestedarrangement of a multiplicity of substantially cylindroidal mixingchambers is attached through a portion of each mixing chamber basal endperiphery in approximate semicircular contact with the inner surface ofthe bottom of said classifier, the assembly of mixing chambers in nestedarrangement being positioned eccentrically on the bottom of saidclassifier, the contacting portion of the innermost mixing chamber beingin substantially symmetrical enveloping arrangement with an opening inthe classifier bottom, the contacting portions of each surroundingmixing chamber being in substantially symmetrical enveloping arrangementwith the next inner mixing chamber, the non-contacting portion of eachmixing chamber basal end periphery constituting a substantial opening atthe basal end of each mixing chamber, said opening of each mixingchamber being directed to the center of the classifier bottom. 1

Kersten Jan. 13, 1900 Anglemeyer Nov. 18, 1930

